Embedded subsystems that provide dedicated functionality within a larger electrical system or circuit often must be tested and tuned. Embedded subsystems may contain digital, analog, mixed-signal and radio frequency (RF) circuits that need to be tuned to improve performance. While standard digital circuits and memory of embedded subsystems can be tested using standard scan test methods and built-in self-test (BIST), analog, mixed signal, RF and other embedded subsystem circuitry having analog performance parameters are not readily tested and tuned.
Problematic to the proper testing and tuning of embedded subsystems having analog performance parameters is the lack of a direct interface between an embedded subsystem and external test equipment, and more particularly between test equipment that is external to a Device Under Test (DUT) having one or more embedded subsystems. Moreover, there is a need to be able to readily perform internal production testing and calibration within an embedded subsystem.